Synthetic resin bottles made of polyethylene terephthalate resins (hereinafter referred to as PET resins) have been widely used in the past as the containers for various drinks and foods. Bottles in a large size with a capacity of 2 liters may be provided with a handle to hold the bottle firmly with a hand, depending on the purposes of use.
Even if the handle is not provided, sometimes a waist portion is provided to make it easy to get hold of the body of the bottle with a hand. For example, bottles are known to have such construction that dents to be used as finger stops are formed in parts of the waist portion which is disposed at a middle height of the body.
The representative construction of a prior-art bottle has dents for use as finger stops, and the dents are formed at a middle height of the body of the bottle. These dents comprise groove-like grips disposed in at least opposed side walls of the body of the bottle. In addition, a dent in a shape of a lateral groove for placing a medicinal finger and another dent for placing a small finger are disposed at a certain space between the dents in one of the opposed body walls positions downward from the grip.    [Patent Document 1] Patent Application No. 2005-112383
In the case of the above-described prior art, the bottle is provided with a dent in the shape of a lateral groove for placing a medicinal finger and another dent for placing a small finger of a hand, in addition to the lateral groove-like grips for placing the thumb and the middle finger of the same hand, i.e., those fingers playing a major role in getting hold of the bottle with a hand. These dents enable the medicinal finger and the small finger, too, to be of help to the gripping action, together with the thumb and the middle finger, when the bottle is held with a hand. As a result, the bottle can be firmly and stably held with a hand.
Each grip comprises a first groove and a second groove which is shallower than the first groove, and the second groove is disposed on both sides of the first groove. Stable gripping force is obtained when the thumb and the middle finger fit in with a step formed on the boundary between the first and second grooves.